The present invention relates generally to conduits for conveying fluids, and particularly to a flexible conduit assembly for conveying a pressurized fluid.
In automotive and industrial applications, several fluids are typically conveyed from one part of the equipment to another, such as fuel, hydraulic and engine oil, and freon gas. In many cases, the fluid must be conveyed under somewhat severe environmental conditions, such as high pressure, wide temperature variations, dirt and vibration. Additionally, since space is usually at a premium, the pipe or conduit must generally follow a tortuous path with several bends of different angles along its length. To add further complexity, the size and weight of the conduit should be minimized, while the reliability of the conduit is maximized. Due to the formidable nature of the above-identified design constraints, a need exists to provide a conduit or piping structure which will both satisfy the above requirements and yet be economical to manufacture and install.
Accordingly, it is a principle object of the present invention to provide a routable and rugged conduit assembly for conveying a pressurized fluid, which is both economical to manufacture and install.
It is another object of the present invention to provide a conduit assembly which is adapted to employ snap-type quick connectors.
It is a further object of the present invention to provide a conduit assembly which is initially flexible, but may be made more rigid before, during or after installation.
It is an additional object of the present invention which may be used to convey a wide variety of fluids under demanding environmental conditions.
To achieve the foregoing objects, the present invention provides a novel conduit assembly for conveying a pressurized fluid wich includes a plastic inner tube for conveying the pressurized fluid, and a flexible metal outer tube disposed coaxially around the inner tube. The outer tube is constructed from one or more interlocking, generally channel-shaped member(s). In one form of the present invention, the outer tube is comprised of two alternately facing, U-shaped metal strips which are helically wound together and slidably engaged. A predetermined radial separation is provided between the exterior diameter of the inner tube and the interior diameter of the outer tube. This predetermined separation permits a limited amount of expansion for inner tube due to the pressure of the fluid and/or the temperature of the fluid (or the environment), while resisting a blowout at normally high pressures and temperatures. While the conduit assembly is initially flexible to facilitate routing, one or more portions of the conduit assembly may be made less flexible, semi-rigid or rigid in order to retain a desired shape of the conduit assembly. For example, the predetermined radial separation described above permits the outer tube to be deformed so that the metal strips of the outer tube are no longer slidably engaged, without causing any appreciable deformation of the inner tube. Additionally, a flexibility reducing material may be injected into the radial separation between the inner and outer tubes, or the flexibility reducing material may be applied to the outer tube along the appropriate portion(s) of the conduit assembly. Additionally, the conduit assembly may be connected between two rigid metal tubes using snap-type quick connectors to form a disparate piping system according to the present invention.